7120/1-1
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General information
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Wellbore history
GeneralWell 7120/1-1 was drilled on the Alpha structure in the north of block 7120/1. The primary objective of the well was to test Palaeozoic carbonates and elastics in a partly fault-bounded/truncated dip closure on the western flank of the Loppa High. Potential Early Triassic sandstones in a low relief dip closure were a secondary objective.OperationsWell 7120/1-1 was spudded on 16 August with the semi-submersible installation "Borgny Dolphin" and drilled to 2569 m where it was suspended on 15 November due to NPD drilling regulations during winter season. On 2 December permission was granted to continue operations and drilling continued to 2610 m. On 26 December the well was again suspended at the request of the Norwegian Petroleum Directorate because of safety considerations in adverse weather conditions. The well was re-entered on 13 March 1986 and drilled to a TD of 4003 m in basement rocks. The well was drilled with seawater and bentonite hi-vis pills down to 485 m. From there to TD gypsum/polymer mud was used with various "Lost Circulation Material" pills to cure mud losses.The well encountered weak hydrocarbon shows from 800 m down to 2200 m and oil shows in Late Permian carbonates (Tempelfjorden Group, Ørret Formation). No intervals of significant reservoir potential were recognized from logs or described from cuttings in the Tertiary or Triassic sections. Below this sequence, three main Permian carbonate units were identified from logs and cuttings description. A porosity range of 5-10% for the limestone sequence between 2415 and 2461 m has been derived from log evaluation. In the basal part of this interval, a black shale was detected with a gas peak of 13% total gas. The lower limestone interval (2607-3277 m) contained weak fluorescence on cuttings from the top down to 2690 m.No coring was attempted in the upper section of this unit due to severe mud losses to the formation. A core was recovered from the base of the interval where alternating limestone, clay stone, marl and shale were described with porosities in the order of 4%. In the lowermost interval (3310-3951 m), dolomite was described as the main lithology with porosities around 3%. No shows were registered. In general, the carbonates had low porosities, but two zones of higher porosity were detected from logs between 2810-2850 m and 2610-2660 m. Two production tests indicated that the limestone was permeable, but no pore fluids were produced.Two cores were cut, one from 3186 m to 3194.5 m, a second from 4000 m – 4003 m in basement rocks. RFT fluid samples were taken at 2798 m ("Slight smell of hydrocarbons"), 3533 m, and 3714.5 m. Bottom hole temperatures from Wire line logging gave a maximum reading of 121 deg C at TD. True bottom hole temperature at TD is thus estimated to 125 °C. The well was plugged and abandoned as a dry hole with oil and gas shows on 21 July 1986.TestingTwo production tests were carried out in the Upper Permian intervals 2810-2855 and 2607-2665 m. Neither interval flowed any pore fluids, not even after acid treatment. Upon nitrogen displacement treatment some fluids were produced, indicating that the formations in both intervals contained water with traces of natural gas, while the interval 2607-2665 m also produced some oil film. Attempts to analyse the oil failed due to the small amounts. -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?YESCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]500.003982.00 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory720.0[m]DC740.0[m]DC850.0[m]DC1070.0[m]DC1400.0[m]DC1550.0[m]DC1610.0[m]DC1680.0[m]DC1870.0[m]DC2030.0[m]DC2050.0[m]DC2154.0[m]DC2226.0[m]DC2250.0[m]DC2283.0[m]DC2310.0[m]DC2319.0[m]DC2327.0[m]DC2354.0[m]DC2363.0[m]DC2373.0[m]DC2379.0[m]DC2390.0[m]DC2420.0[m]DC2466.0[m]DC2535.0[m]DC2595.0[m]DC2607.0[m]DC2899.0[m]DC3142.0[m]DC -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit367490490692692110622852285231523732403240324302458 -
Geochemical information
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Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf14.38 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]ACL GR24052477ACSIG24052477CBL7452090CBL VDL20002413CDL CNL CAL GR4602480DIFL ACL SP GR3602422DIPLOG20862416FMT21362412FMT24252466MLL DLL GR24132480SWS4952478 -
Casing and leak–off tests
Casing and leak–off tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30468.536480.00.00LOTSURF.COND.201101.0261112.01.37LOTINTERM.13 3/82093.017 1/22107.01.50LOTINTERM.9 5/82569.012 1/42569.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured3781.03WATER BASED4561.03WATER BASED4801.04120.0WATER BASED5811.0460.0WATER BASED7251.0541.0WATER BASED8001.0742.0WATER BASED8321.0666.0WATER BASED11121.1264.0WATER BASED11581.1237.0WATER BASED12531.1245.0WATER BASED13401.1350.0WATER BASED14491.1750.0WATER BASED14701.1755.0WATER BASED15231.1754.0WATER BASED16281.1749.0WATER BASED16921.1747.0WATER BASED17571.1748.0WATER BASED18341.1746.0WATER BASED18681.1748.0WATER BASED19591.1746.0WATER BASED20751.1745.0WATER BASED21071.1717.0WATER BASED22811.2849.0WATER BASED23071.3755.0WATER BASED23731.2555.0WATER BASED23761.2647.0WATER BASED24001.2746.0WATER BASED24111.2750.0WATER BASED24261.3047.0WATER BASED24261.2748.0WATER BASED24471.2843.0WATER BASED24531.2848.0WATER BASED24801.3445.0WATER BASED24941.3745.0WATER BASED25371.3745.0WATER BASED25691.3724.0WATER BASED -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit4001.30[m ]3192.55[m ]3194.20[m ]3190.70[m ]3188.65[m ]3187.35[m ]3186.62[m ] -
Pressure plots
Pressure plots The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.Pressure plots Document nameDocument formatDocument size [MB]PDF0.28